1. Field of the Invention
The present invention relates to a mobile terminal, and more particularly to a touch key assembly structured to include a light source for lighting touch keys.
2. Discussion of the Related Art
A mobile terminal is one type of portable electronic device capable of wireless communication in a mobile environment. Common mobile terminals include mobile phones, personal digital assistants (PDSs), and the like. Consumers have demanded mobile terminals with increasingly thinner dimensions. In many cases, thinner mobile terminals are more convenient to carry.
A typical mobile terminal includes a keypad having key buttons for inputting numbers, letters, and other control commands. An example of a typical keypad of a conventional mobile terminal is shown in FIG. 1, which is a cross-sectional view of a portion of a keypad commonly found in a conventional mobile terminal.
As shown in this figure, keypad 10 includes key buttons 12 exposed to receive contact by a user pressing downward on the buttons. Dome switches 16 are arranged below key buttons 12 and are mounted on an upper surface of circuit board 14. The key buttons are configured to produce signals responsive to user manipulation. Pad 13 is shown attached to a lower surface of key buttons 12, and elastically transforms upon pressing of the key buttons. One purpose of the pad is to assist in the pressurizing of dome switches 16.
Key buttons 12 are shown exposed to the outside of terminal case 11, and typically include characters, numerals, letters, and the like on an upper surface of the button. The buttons are structured to transmit light generated by light emitting diodes (LEDs) 15.
Pad 13 is shown having push protrusions 17, which also assist in pressurizing dome switches 16 upon pressing of key buttons 12. LEDs 15 are often implemented for illuminating the key buttons. The LEDs provide light to the key buttons, which is useful when the mobile terminal is used in a dimly lit environment.
As FIG. 1 illustrates, LEDs 15 protrude from an upper surface of circuit board 14. The LEDs consume significant amounts of space such that they are positioned within a gap formed between pad 13 and circuit board 14. A drawback of this arrangement is that the gap necessarily increases the thickness of the mobile terminal. Another disadvantage is that the dome switches block significant portions of light emitted by the LEDs. As a result, the number of LEDs required to light the various key buttons is often increased so that each key button is sufficiently illuminated. Increasing the number of LEDs consequently results in an undesirable increase in the power requirements of the mobile terminal.